The invention pertains to metal cutting machines and methods. More particularly, the invention relates to machines that designed to divide ring forgings made of titanium and related materials into precision measured ring sections for further processing.
Titanium and related materials are typically used for the manufacture of aircraft engine parts and other high-stress, high-temperature applications. These materials are necessarily difficult to cut or machine and tend to be expensive so it is desirable that waste should be minimized. These materials cannot be cut effectively using abrasive cut-off wheels or saws and managing the heat and waste material produced in typical dividing operations can be problematical. Cutting procedures that involve a machine lathe and an orthogonally mounted cutter bar tend to bind as the cut into the rotating ring forging becomes deeper. Further, heating of the ring forging and the tool also increases as the cut becomes deeper, affecting the accuracy of the cut. Also as the cut becomes deeper, it becomes more difficult to clear the chip stream from the area of the cut, further causing binding and possible tool breakage or damage to the rings being cut. It is often desirable to divide a piece of ring forging of such material into nearly identical size ring sections for further forging or machining. If the ring sections can be identically sized and a minimum of material lost in the cutting, the process will be more economical.
U.S. Pat. No. 5,806,386 issued to Risse, is directed to a parting off tool for a lathe having a cutting edge and a rubbing pad. The tool body, a planar plate of stainless steel or the like, has its base located within a tool holder or post. A cutting tip is located on the working edge and has a short sharp edge parallel to the axis of piece. A cutting gap is an interruption in the continuity of the working edge and leads into a chip clearance area that is an aperture completely through the thickness of tool body. Across the cutting gap from the cutting tip a rubbing pad is located. The rubbing pad may be a polished hardened removable attachment or simply may be a length of the working edge.
U.S. Pat. No. 4,452,112, issued to Alexander describes a method of parting metallic rings in which the vibrations generated during heavy-duty operations are minimized by the additional step of supporting the tool holder with side plates. The parting tool, an indexable and disposable insert, has a bore through its center for receiving a fastener that also is received by a shim seat that is seated upon tool holder. The tool holder has side plates to support the tool holder from vibrations due to the extremely high pressures generated in the parting of very large rings. The parting tool engages the surface of the rotating ring below the horizontal plane of the center of rotation.
U.S. Pat. No. 4,052,822 issued to Obear is directed to a method and apparatus for abrasively cutting objects by making a score cut with a previously used worn down abrasive cutting wheel. The abrasive sawing machine has a main frame with a saw housing which positions a large saw or cutting wheel and a smaller saw or cutting wheel for engagement with a metal object, such as a billet to be cut. The large cutting wheel is mounted on an arbor and is used as the main cutting wheel until its diameter is worn down and it becomes less efficient for cutting and is limited in size of the billets that can effectively be cut. The used wheel is then employed as the smaller cutting wheel for making the initial scoring cut. The smaller wheel is provided with an arbor that is located diametrically opposite the larger wheel providing maximum clearance between the wheels as they begin to approach one another while simultaneously cutting the billet.
The smaller cutting wheel, though of the same thickness as the larger wheel, is much more rigid and thus does not skid along the surface of the billet during the initial scoring cut. The small wheel is rotated in the opposite direction of that of the billet to provide a preferred cutting for accurate alignment of the scoring cut while recognizing that a dressing type wear will occur with shorter life. Once the scoring cut is made sufficiently deep, the larger cutting wheel is moved into engagement within the scoring cut. The larger wheel rotates in a direction similar to that of the billet, which is the preferred direction for maximum wearing life of the wheel.
U.S. Pat. No. 4,549,678 issued to Fuminier, discloses a method and apparatus for separating a cut tube end from a work piece to avoid the risk of the end damaging the cutting tool. During the cutting operation, the tool mills a circular groove in the wall of the tube. As tool starts the groove, a jack drives a separator roller in the direction of the groove and a wedge enters the groove with the roller centering itself on the groove. After the cut end is separated, a support arm receives it and stops its fall. The separator apparatus prevents the cut end from falling onto the edge of cutting tool, and damaging it.
U.S. Pat. No. 4,302,958 issued to Andriessen et al., is directed to a parting off rolling tool having three rollers. The parting off tool has a main tool head and a second tool head. The main tool head has a part off rolling tool and a further tool that is a grooving tool of smaller diameter having a V-shaped working surface. The second tool head has only a rolling tool. As the rolling tools and advance through the tube stock, the grooving tool reaches the surface of the tube stock so that by the time the parting groove is completed, the grooving tool has formed a substantially V-shaped circumferential locating groove that is spaced axially from groove by the center-to-center distance L. As the tube stock is advanced for the next cut, error is eliminated by locating the rolling tools in the groove.
While other variations exist, the above described designs for ring-cutting machines are typical of those encountered in the prior art. It is an objective of the present invention to provide for cutting of rings of precisely described dimensions from titanium and related materials. It is a further objective to provide such precision cutting with a minimum of waste. It is yet another objective of the invention to minimize heating of both the cutting tool and the work piece. It is still another objective to minimize any pollution produced by the cutting process. Finally, it is an objective of the invention to provide the above-described capabilities in an inexpensive and durable machine, which is capable of extended duty cycles, and that may be easily repaired and maintained.
While some of the objectives of the present invention are disclosed in the prior art, none of the inventions found include all of the requirements identified.
The present invention addresses all of the deficiencies of prior art ring cutting inventions and satisfies all of the objectives described above.
An apparatus for cutting rings from ring forgings of titanium or related materials providing the desired features may be constructed from the following components. Means for removably holding and rotating the ring forging about a longitudinal axis are provided. The longitudinal axis extends through a centerline of the ring forging. Means are provided for rotating the ring forging at at least one speed and in at least one direction. A tool holder is adjustably mounted spaced from and parallel to the axis. Means are provided for controlling a displacement of the tool holder from the means for holding the ring forging along the axis, thereby allowing an operator to determine a thickness of a ring to be cut from the ring forging. Means are provided for controlling a displacement of the tool holder from the axis to affect cutting of the ring from the ring forging.
First and second cutter bars are provided. The first and second cutter bars are removably mounted to the tool holder such that the cutter bars are positioned orthogonally with respect to the axis. The first cutter bar includes a first cutting bit. The first cutting bit has a first cutting edge of a first predetermined width. The first cutting edge is positioned to move along a diameter of the ring forging toward the axis. The second cutter bar includes a second cutting bit. The second cutting bit has a second cutting edge of a second predetermined width. The second predetermined width is wider than the first predetermined width. The second cutting edge is positioned to move along a line parallel to and spaced from the diameter. The line is coplanar with the diameter. The second cutting bit is located to engage the ring forging after the first cutting bit engages the ring forging as the first cutting edge is moved along the diameter.
In a variant of the invention, the apparatus for cutting rings from ring forgings of titanium or related materials may be constructed from the following components. A horizontal mounting surface is provided. A machine base is fixedly attached to the mounting surface. A rotating headstock is fixedly attached to the machine base. The headstock has a longitudinal axis of rotation parallel to the horizontal mounting surface. The headstock has a front face. The front face is orthogonal to the axis of rotation of the headstock. The headstock is capable of providing rotation at at least one speed and capable of providing rotation in at least one direction.
The front face is adapted to removably attach a clamping means parallel to the front face. The clamping means is capable of mounting a ring forging such that the centerline of the forging is collinear with the longitudinal axis of rotation of the rotating headstock.
A tool holder is adjustably mounted spaced from and parallel to the axis. Means are provided for controlling a displacement of the tool holder from the front face of the headstock along the axis, thereby allowing an operator to determine a thickness of a ring to be cut from the ring forging. Means are provided for controlling a displacement of the tool holder from the axis to affect cutting of the ring from the ring forging. First and second cutter bars are provided. The first and second cutter bars are removably mounted to the tool holder such that the cutter bars are positioned orthogonally with respect to the axis.
The first cutter bar includes a first cutting bit. The first cutting bit has a first cutting edge of a first predetermined width. The first cutting edge is positioned to move along a diameter of the ring forging toward the axis. The second cutter bar includes a second cutting bit. The second cutting bit has a second cutting edge of a second predetermined width. The second predetermined width is wider than the first predetermined width. The second cutting edge is positioned to move along a line parallel to and spaced from the diameter. The line is coplanar with the diameter. The second cutting bit is located to engage the ring forging after the first cutting bit engages the ring forging as the first cutting edge is moved along the diameter.
When the first cutting bit engages the ring forging as the forging is rotated toward the first cutting edge a cut of the first predetermined width will be produced. When the second cutting bit engages the forging, the cut will be widened to the second predetermined width and chips will be removed from the cut and heat produced by the first cutting bit will be reduced.
In a further variant of the invention, the clamping means is a centering three-jaw chuck. In still a further variant, the means for controlling the displacement of the tool holder from the axis further comprises a horizontal drive mechanism. The drive mechanism is capable of moving the tool holder toward the axis of rotation at at least one predetermined speed.
In another variant of the invention, each of the first and second cutter bars include a flattened rectangular bar. The bar has a first end, a second end, first and second parallel side edges, a first uniform thickness and at least one receiving notch. The receiving notch is located at either the first or second end adjacent either the first or second side edges. The receiving notch has an upper edge and a lower edge. The edges taper toward each other and terminate in a rounded release opening. The upper and lower edges have a convex profile and are sized and shaped to receive a tapered cutting bit.
At least one tapered cutting bit is provided. Each of the cutting bits has a cutting edge and upper and lower edges that taper toward each other. The upper and lower edges have a concave profile sized and shaped to fit slidably the convex profile of the upper and lower edges of the receiving notch. The first or second end of the bar is relieved so that when the cutting bit is installed in the receiving notch, the cutting edge will protrude beyond the first or second ends of the bar.
In still another variant, the tool holder includes a base. The base includes means for removably mounting the tool holder to the means for controlling a displacement of the tool holder. A tool bar mounting surface is provided. The surface is orthogonal to the base and orthogonal to the axis of rotation of the headstock. A horizontal receiving slot is located in the tool bar mounting surface and has parallel upper and lower edges. The horizontal receiving slot is sized and shaped to slidably fit the rectangular bar of the first cutter bar. The horizontal receiving slot has a depth slightly less than the first uniform thickness. The horizontal slot is located so that the first cutting edge of the first cutter bit can be moved along the diameter of the ring forging.
An angled receiving slot is provided. The angled slot is located in the tool bar mounting surface and has parallel upper and lower edges and is sized and shaped to slidably fit the rectangular bar of the second cutter bar. The angled receiving slot has a depth slightly less than the first uniform thickness. The angled slot is located so that the second cutting edge of the second cutter bit can be moved along the line parallel to and spaced from the diameter. The line is coplanar with the diameter. Means are provided for securing each of the first and second cutter bars to the tool holder.
In a final variation of the invention, the means for securing each of the first and second cutter bars to the tool holder includes at least two threaded holes penetrating the tool bar mounting surface on either side of the horizontal slot and the angled slot perpendicular to the mounting surface. At least one rigid plate is provided. The rigid plate has at least two holes located to slidably fit threaded bolts sized to fit the threaded holes. At least two bolts are provided. The bolts are sized and shaped to penetrate the holes in the rigid plate and engage the threaded holes without reaching a bottom of the threaded holes. When the first and second tool bars are located in the horizontal slot and the angled slot and the bolts penetrate the rigid plate and threadedly engage the threaded holes and are tightened, the first and second tool bars will be removably attached to the tool holder.